Memory is one type of integrated circuitry, and is used in computer systems for storing data. Memory may be fabricated in one or more arrays of individual memory cells. Memory cells may be written to, or read from, using bit lines (which may also be referred to as digit lines, data lines, sense lines, or data/sense lines) and access lines (which may also be referred to as word lines). The bit lines may conductively interconnect memory cells along columns of the array, and the access lines may conductively interconnect memory cells along rows of the array. Each memory cell may be uniquely addressed through the combination of a bit line and an access line.
Memory cells may be volatile or non-volatile. Non-volatile memory cells can store data for extended periods of time including when the computer is turned off. Volatile memory dissipates and therefore requires being refreshed/rewritten, in many instances multiple times per second. Regardless, memory cells are configured to retain or store memory in at least two different selectable states. In a binary system, the states are considered as either a “0” or a “1”. In other systems, at least some individual memory cells may be configured to store more than two levels or states of information.
A field effect transistor is one type of electronic component that may be used in a memory cell. These transistors comprise a pair of conductive source/drain regions having a semiconductive channel region there-between. A conductive gate is adjacent the channel region and separated there-from by a thin gate insulator. Application of a suitable voltage to the gate allows current to flow from one of the source/drain regions to the other through the channel region. When the voltage is removed from the gate, current is largely prevented from flowing through the channel region. Field effect transistors may also include additional structure, for example reversibly programmable charge storage/trap regions as part of the gate construction between the gate insulator and the conductive gate.
One electronic component associated with a memory cell is a sense amplifier. These devices are typically electrically coupled with one or more bit lines of a column of memory cells within an array. The sense amplifier at least in part is used to detect what value is stored in a memory cell and reporting that value amplified at an output of the sense amplifier.